Electron paramagnetic resonance spectra of VO 2+ ions in NaI–Na 2O–K 2O–B 2O 3 mixed alkali glasses

Abstract

The electron paramagnetic resonance (EPR) spectra of VO 2+ ions in the 15 NaI–(15 − x)Na 2O– xK 2O–B 2O 3 mixed alkali glass system were analysed at X-band frequencies at 310 K. The spin-Hamiltonian parameters and covalency rates were evaluated. It was found that the V 4+ ions exist as vanadyl (VO 2+) ions and are in an octahedral coordination with a tetragonal compression. The covalency rates (1 − α 2) and (1 − υ 2) indicate moderate covalency for the σ- and the π-bonds. It was observed that the spin-Hamiltonian parameters depend slightly on the relative alkali ion concentrations of K and Na.